An absorbable monofilament suture will be prepared from a biomaterial known as poly-4-hydroxybutyrate (P4HB). The P4HB will be derived using a genetically engineered fermentation system that is based on a class of natural polyesters, known as PHAs (or polyhydroxyalkanoates). This fermentation system is ideally suited for the production of P4HB based polymers. The new suture will be prepared by melt extrusion and is anticipated to have better handling properties than the existing monofilament sutures, and a longer retention of strength. The latter is expected to allow the use of a monofilament absorbable suture for patients previous requiring long-term wound support with a non- absorbable suture for patients with conditions that compromise wound healing, such as malignancy, compromised immune system, obesity, nutritional impairment, and diabetes. It may also be useful in the treatment of orthopedic patients and for fascia closure. The specific aims of this research are to: (1) produce the biomaterial P4HB, (2) prepare sutures/fibers of P4HB, (3) characterize the P4HB sutures, and (40 determine the break the break strength retention of the sutures in vivo as well as tissue reaction and the absorption rate. PROPOSED COMMERCIAL APPLICATIONS: The research will provide a new monofilament fiber that will be used in the development of bioabsorbable, medical products, such as sutures, tissue engineering scaffolds, surgical meshes and fabrics.